In the event of a Clinton-Kaine victory, state law requires Gov. Terry McAuliffe (D) to appoint someone to fill Kaine’s Senate seat for about a year. After that, a special election would be held, coinciding with the 2017 governor’s race, and the winner would have to run again for a full six-year term the following year.

“These vacancies don’t come up very often so there are a lot of people who would be interested if the opportunity presented itself,” said Stephen J. Farnsworth, a political scientist at the University of Mary Washington.

Top Democratic possibilities include sitting congressmen such as Don Beyer, Robert C. “Bobby” Scott or Gerald E. Connolly. Others say Attorney General Mark R. Herring or Brian Moran, a member of McAuliffe’s cabinet, would be smart choices.

If McAuliffe decides to nominate a placeholder who would not seek election, former governor L. Douglas Wilder or recently retired Norfolk Mayor Paul Fraim are good options, experts say. However, that move would rob the eventual candidate of the advantage of incumbency.

Potential Republican candidates in 2017 would likely include former attorney general Ken Cuccinelli II, Rep. Rob Wittman or Rep. Barbara Comstock. And Rep. Dave Brat, the tea party hero who ousted Majority Leader Eric Cantor two years ago, told CNN that he would consider a run if Kaine wins.

“If I can best serve the country by running for that position then I will certainly entertain that challenge in the future if that choice becomes a reality,” Brat said in a statement to The Washington Post.

The stakes are high for both parties in a midterm election where the seat could tip the balance of power in the closely divided Senate. Republicans haven’t held a U.S. Senate seat since John Warner retired in 2009, but they came close in 2014 when GOP strategist Ed Gillespie challenged Sen. Mark Warner.

If Hillary Clinton wins the White House, the GOP could try to capi­tal­ize on voter backlash against the Democrat. Virginia, with its off-year gubernatorial race, reliably elects a standard-bearer from the opposite party of the winner of the presidency.

“Everybody will be watching Virginia,” said Dan Scandling, a longtime aide to former Republican congressman Frank R. Wolf. “It’ll be a referendum on the presidency. Always is, always has been. And both sides would pour ungodly amounts of money into the race to win the seat or hold the seat.”

McAuliffe would have to choose someone who could raise the roughly $20 million necessary to run statewide in back-to-back years, wouldn’t cost Democrats a seat elsewhere and could drive turnout to help others on the ticket, observers say.

He’s not quite there yet. “We will respond to that circumstance if it occurs,” his spokesman, Brian Coy, said.

In the meantime, here’s a look at some of the possible contenders.

For Beyer, a Senate seat would cap a career of public service for the man who was lieutenant governor from 1990 to 1998, ambassador to Switzerland and Liechtenstein and is currently seeking a second term in Congress. The owner of Northern Virginia car dealerships with ubiquitous radio ads, Beyer has proved he can build a war chest to run statewide.

His district, which includes Arlington County and Alexandria, isn’t likely to fall into Republican hands anytime soon. The same is true of the Fairfax district represented by Connolly, the four-term congressman and another potential Senate pick.

Scott is the state’s lone African American congressman but will likely be joined by a second next year. State Sen. A. Donald McEachin (D-Henrico) won the primary election for a newly drawn Richmond-area seat that leans heavily Democratic.

Although he will just barely have served in federal office, some note that McAuliffe could tap McEachin for the Senate without jeopardizing a seat in Congress. Or he could turn to his former secretary of the commonwealth, Levar Stoney, who is running for mayor of Richmond and is African American.

Democrats, who so far have two white men on the 2017 ticket, have tried to recruit women for statewide office, including state Del. Jennifer L. McClellan (D-Richmond), a corporate attorney who is African American, and Molly Ward, secretary of natural resources and former mayor of Hampton. Either would be on the Senate short list as could be Kaine’s wife, Anne Holton, state education secretary and former first lady.

Herring declined last year to run for governor, sparking rumors that he stepped aside in exchange for assurances that he would be in line for Kaine’s seat. But experts say keeping the powerful role of attorney general in Democratic hands is key to the party’s agenda, and Herring is all in when it comes to reelection.

McAuliffe could turn to Moran, the secretary of public safety and homeland security whose negotiation of a grand compromise on gun laws raised his profile during this year’s legislative session.

Republicans would also be in the hunt for Kaine’s seat in a special election.

Cuccinelli, the polarizing former attorney general, is frequently mentioned by observers. Despite drawing the ire of some fellow Republicans for supporting Sen. Ted Cruz for president, Cuccinelli remains a popular figure within the party.

Wittman, who is currently putting together a campaign for governor, could decide to change course and make a bid for the Senate, clearing the GOP field for Gillespie, the party’s gubernatorial front-runner.

Comstock would also be a tough opponent, assuming she wins reelection to a second term this year and made the right bet declining to endorse Donald Trump for president.